X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FBenchmark.pm;h=cda764f6ca317bc9e7b9fe0a2fc1a98d5d9fcb4e;hb=08411240a1e5278b0232e1455d984110b1c5343b;hp=f4a81495a0eee6451d056b012c575cb0eb09397c;hpb=3c6312e9cc02e5b354acc85db6d5532c134bd61a;p=p5sagit%2Fp5-mst-13.2.git diff --git a/lib/Benchmark.pm b/lib/Benchmark.pm index f4a8149..cda764f 100644 --- a/lib/Benchmark.pm +++ b/lib/Benchmark.pm @@ -2,16 +2,12 @@ package Benchmark; =head1 NAME -Benchmark - benchmark running times of code - -timethis - run a chunk of code several times - -timethese - run several chunks of code several times - -timeit - run a chunk of code and see how long it goes +Benchmark - benchmark running times of Perl code =head1 SYNOPSIS + use Benchmark qw(:all) ; + timethis ($count, "code"); # Use Perl code in strings... @@ -26,14 +22,50 @@ timeit - run a chunk of code and see how long it goes 'Name2' => sub { ...code2... }, }); + # cmpthese can be used both ways as well + cmpthese($count, { + 'Name1' => '...code1...', + 'Name2' => '...code2...', + }); + + cmpthese($count, { + 'Name1' => sub { ...code1... }, + 'Name2' => sub { ...code2... }, + }); + + # ...or in two stages + $results = timethese($count, + { + 'Name1' => sub { ...code1... }, + 'Name2' => sub { ...code2... }, + }, + 'none' + ); + cmpthese( $results ) ; + $t = timeit($count, '...other code...') print "$count loops of other code took:",timestr($t),"\n"; + $t = countit($time, '...other code...') + $count = $t->iters ; + print "$count loops of other code took:",timestr($t),"\n"; + =head1 DESCRIPTION The Benchmark module encapsulates a number of routines to help you figure out how long it takes to execute some code. +timethis - run a chunk of code several times + +timethese - run several chunks of code several times + +cmpthese - print results of timethese as a comparison chart + +timeit - run a chunk of code and see how long it goes + +countit - see how many times a chunk of code runs in a given time + + =head2 Methods =over 10 @@ -57,6 +89,10 @@ Enables or disable debugging by setting the C<$Benchmark::Debug> flag: $t = timeit(10, ' 5 ** $Global '); debug Benchmark 0; +=item iters + +Returns the number of iterations. + =back =head2 Standard Exports @@ -126,11 +162,6 @@ Returns a hash of Benchmark objects, keyed by name. Returns the difference between two Benchmark times as a Benchmark object suitable for passing to timestr(). -=item timesum ( T1, T2 ) - -Returns the sum of two Benchmark times as a Benchmark object suitable -for passing to timestr(). - =item timestr ( TIMEDIFF, [ STYLE, [ FORMAT ] ] ) Returns a string that formats the times in the TIMEDIFF object in @@ -167,17 +198,62 @@ Clear all cached times. =item cmpthese ( COUT, CODEHASHREF, [ STYLE ] ) -=item cmpthese ( RESULTSHASHREF ) +=item cmpthese ( RESULTSHASHREF, [ STYLE ] ) + +Optionally calls timethese(), then outputs comparison chart. This: + + cmpthese( -1, { a => "++\$i", b => "\$i *= 2" } ) ; + +outputs a chart like: -Optionally calls timethese(), then outputs comparison chart. This -chart is sorted from slowest to highest, and shows the percent -speed difference between each pair of tests. Can also be passed -the data structure that timethese() returns: + Rate b a + b 2831802/s -- -61% + a 7208959/s 155% -- - $results = timethese( .... ); +This chart is sorted from slowest to fastest, and shows the percent speed +difference between each pair of tests. + +c can also be passed the data structure that timethese() returns: + + $results = timethese( -1, { a => "++\$i", b => "\$i *= 2" } ) ; cmpthese( $results ); -Returns the data structure returned by timethese(). +in case you want to see both sets of results. + +Returns a reference to an ARRAY of rows, each row is an ARRAY of cells from the +above chart, including labels. This: + + my $rows = cmpthese( -1, { a => '++$i', b => '$i *= 2' }, "none" ); + +returns a data structure like: + + [ + [ '', 'Rate', 'b', 'a' ], + [ 'b', '2885232/s', '--', '-59%' ], + [ 'a', '7099126/s', '146%', '--' ], + ] + +B: This result value differs from previous versions, which returned +the C result structure. If you want that, just use the two +statement C...C idiom shown above. + +Incidently, note the variance in the result values between the two examples; +this is typical of benchmarking. If this were a real benchmark, you would +probably want to run a lot more iterations. + +=item countit(TIME, CODE) + +Arguments: TIME is the minimum length of time to run CODE for, and CODE is +the code to run. CODE may be either a code reference or a string to +be eval'd; either way it will be run in the caller's package. + +TIME is I negative. countit() will run the loop many times to +calculate the speed of CODE before running it for TIME. The actual +time run for will usually be greater than TIME due to system clock +resolution, so it's best to look at the number of iterations divided +by the times that you are concerned with, not just the iterations. + +Returns: a Benchmark object. =item disablecache ( ) @@ -190,6 +266,11 @@ Enable caching of timings for the null loop. The time taken for COUNT rounds of the null loop will be calculated only once for each different COUNT used. +=item timesum ( T1, T2 ) + +Returns the sum of two Benchmark times as a Benchmark object suitable +for passing to timestr(). + =back =head1 NOTES @@ -197,7 +278,7 @@ different COUNT used. The data is stored as a list of values from the time and times functions: - ($real, $user, $system, $children_user, $children_system) + ($real, $user, $system, $children_user, $children_system, $iters) in seconds for the whole loop (not divided by the number of rounds). @@ -222,6 +303,45 @@ calls like these: Caching is off by default, as it can (usually slightly) decrease accuracy and does not usually noticably affect runtimes. +=head1 EXAMPLES + +For example, + + use Benchmark qw( cmpthese ) ; + $x = 3; + cmpthese( -5, { + a => sub{$x*$x}, + b => sub{$x**2}, + } ); + +outputs something like this: + + Benchmark: running a, b, each for at least 5 CPU seconds... + Rate b a + b 1559428/s -- -62% + a 4152037/s 166% -- + + +while + + use Benchmark qw( timethese cmpthese ) ; + $x = 3; + $r = timethese( -5, { + a => sub{$x*$x}, + b => sub{$x**2}, + } ); + cmpthese $r; + +outputs something like this: + + Benchmark: running a, b, each for at least 5 CPU seconds... + a: 10 wallclock secs ( 5.14 usr + 0.13 sys = 5.27 CPU) @ 3835055.60/s (n=20210743) + b: 5 wallclock secs ( 5.41 usr + 0.00 sys = 5.41 CPU) @ 1574944.92/s (n=8520452) + Rate b a + b 1574945/s -- -59% + a 3835056/s 144% -- + + =head1 INHERITANCE Benchmark inherits from no other class, except of course @@ -230,7 +350,7 @@ for Exporter. =head1 CAVEATS Comparing eval'd strings with code references will give you -inaccurate results: a code reference will show a slower +inaccurate results: a code reference will show a slightly slower execution time than the equivalent eval'd string. The real time timing is done using time(2) and @@ -246,6 +366,10 @@ The system time of the null loop might be slightly more than the system time of the loop with the actual code and therefore the difference might end up being E 0. +=head1 SEE ALSO + +L - a Perl code profiler + =head1 AUTHORS Jarkko Hietaniemi >, Tim Bunce > @@ -263,7 +387,13 @@ functionality. September, 1999; by Barrie Slaymaker: math fixes and accuracy and efficiency tweaks. Added cmpthese(). A result is now returned from -timethese(). +timethese(). Exposed countit() (was runfor()). + +December, 2001; by Nicholas Clark: make timestr() recognise the style 'none' +and return an empty string. If cmpthese is calling timethese, make it pass the +style in. (so that 'none' will suppress output). Make sub new dump its +debugging output to STDERR, to be consistent with everything else. +All bugs found while writing a regression test. =cut @@ -277,8 +407,12 @@ sub _doeval { eval shift } use Carp; use Exporter; @ISA=(Exporter); -@EXPORT=qw(timeit timethis timethese timediff timesum timestr); -@EXPORT_OK=qw(clearcache clearallcache cmpthese disablecache enablecache); +@EXPORT=qw(timeit timethis timethese timediff timestr); +@EXPORT_OK=qw(timesum cmpthese countit + clearcache clearallcache disablecache enablecache); +%EXPORT_TAGS=( all => [ @EXPORT, @EXPORT_OK ] ) ; + +$VERSION = 1.04; &init; @@ -307,13 +441,14 @@ sub disablecache { $cache = 0; } # --- Functions to process the 'time' data type sub new { my @t = (time, times, @_ == 2 ? $_[1] : 0); - print "new=@t\n" if $debug; + print STDERR "new=@t\n" if $debug; bless \@t; } sub cpu_p { my($r,$pu,$ps,$cu,$cs) = @{$_[0]}; $pu+$ps ; } sub cpu_c { my($r,$pu,$ps,$cu,$cs) = @{$_[0]}; $cu+$cs ; } sub cpu_a { my($r,$pu,$ps,$cu,$cs) = @{$_[0]}; $pu+$ps+$cu+$cs ; } sub real { my($r,$pu,$ps,$cu,$cs) = @{$_[0]}; $r ; } +sub iters { $_[0]->[5] ; } sub timediff { my($a, $b) = @_; @@ -338,19 +473,20 @@ sub timestr { my @t = @$tr; warn "bad time value (@t)" unless @t==6; my($r, $pu, $ps, $cu, $cs, $n) = @t; - my($pt, $ct, $t) = ($tr->cpu_p, $tr->cpu_c, $tr->cpu_a); + my($pt, $ct, $tt) = ($tr->cpu_p, $tr->cpu_c, $tr->cpu_a); $f = $defaultfmt unless defined $f; # format a time in the required style, other formats may be added here $style ||= $defaultstyle; + return '' if $style eq 'none'; $style = ($ct>0) ? 'all' : 'noc' if $style eq 'auto'; my $s = "@t $style"; # default for unknown style $s=sprintf("%2d wallclock secs (%$f usr %$f sys + %$f cusr %$f csys = %$f CPU)", - @t,$t) if $style eq 'all'; + $r,$pu,$ps,$cu,$cs,$tt) if $style eq 'all'; $s=sprintf("%2d wallclock secs (%$f usr + %$f sys = %$f CPU)", $r,$pu,$ps,$pt) if $style eq 'noc'; $s=sprintf("%2d wallclock secs (%$f cusr + %$f csys = %$f CPU)", $r,$cu,$cs,$ct) if $style eq 'nop'; - $s .= sprintf(" @ %$f/s (n=$n)", $n / ( $pu + $ps )) if $n; + $s .= sprintf(" @ %$f/s (n=$n)", $n / ( $pu + $ps )) if $n && $pu+$ps; $s; } @@ -392,12 +528,10 @@ sub runloop { # -0.01, +0. If we don't wait, then it's more like -0.01, +0.01. This # may not seem important, but it significantly reduces the chances of # getting a too low initial $n in the initial, 'find the minimum' loop - # in &runfor. This, in turn, can reduce the number of calls to + # in &countit. This, in turn, can reduce the number of calls to # &runloop a lot, and thus reduce additive errors. my $tbase = Benchmark->new(0)->[1]; - do { - $t0 = Benchmark->new(0); - } while ( $t0->[1] == $tbase ); + while ( ( $t0 = Benchmark->new(0) )->[1] == $tbase ) {} ; &$subref; $t1 = Benchmark->new($n); $td = &timediff($t1, $t0); @@ -415,7 +549,7 @@ sub timeit { if ($cache && exists $cache{$cache_key} ) { $wn = $cache{$cache_key}; } else { - $wn = &runloop($n, ref( $code ) ? sub { undef } : '' ); + $wn = &runloop($n, ref( $code ) ? sub { } : '' ); # Can't let our baseline have any iterations, or they get subtracted # out of the result. $wn->[5] = 0; @@ -437,8 +571,8 @@ my $default_for = 3; my $min_for = 0.1; -sub runfor { - my ($code, $tmax) = @_; +sub countit { + my ( $tmax, $code ) = @_; if ( not defined $tmax or $tmax == 0 ) { $tmax = $default_for; @@ -446,7 +580,7 @@ sub runfor { $tmax = -$tmax; } - die "runfor(..., $tmax): timelimit cannot be less than $min_for.\n" + die "countit($tmax, ...): timelimit cannot be less than $min_for.\n" if $tmax < $min_for; my ($n, $tc); @@ -469,7 +603,9 @@ sub runfor { # accuracy since we're not couting these times. $n = int( $tpra * 1.05 * $n / $tc ); # Linear approximation. my $td = timeit($n, $code); - $tc = $td->[1] + $td->[2]; + my $new_tc = $td->[1] + $td->[2]; + # Make sure we are making progress. + $tc = $new_tc > 1.2 * $tc ? $new_tc : 1.2 * $tc; } # Now, do the 'for real' timing(s), repeating until we exceed @@ -498,6 +634,7 @@ sub runfor { $ttot = $utot + $stot; last if $ttot >= $tmax; + $ttot = 0.01 if $ttot < 0.01; my $r = $tmax / $ttot - 1; # Linear approximation. $n = int( $r * $ntot ); $n = $nmin if $n < $nmin; @@ -523,7 +660,7 @@ sub timethis{ $title = "timethis $n" unless defined $title; } else { $fort = n_to_for( $n ); - $t = runfor($code, $fort); + $t = countit( $fort, $code ); $title = "timethis for $fort" unless defined $title; $forn = $t->[-1]; } @@ -560,7 +697,8 @@ sub timethese{ print " ", join(', ',@names) unless $style eq 'none'; unless ( $n > 0 ) { my $for = n_to_for( $n ); - print ", each for at least $for CPU seconds" unless $style eq 'none'; + print ", each" if $n > 1 && $style ne 'none'; + print " for at least $for CPU seconds" unless $style eq 'none'; } print "...\n" unless $style eq 'none'; @@ -575,10 +713,9 @@ sub timethese{ } sub cmpthese{ - my $results = ref $_[0] ? $_[0] : timethese( @_ ); + my ($results, $style) = ref $_[0] ? @_ : ( timethese( @_[0,1,2] ), $_[2] ) ; - return $results - if defined $_[2] && $_[2] eq 'none'; + $style = "" unless defined $style; # Flatten in to an array of arrays with the name as the first field my @vals = map{ [ $_, @{$results->{$_}} ] } keys %$results; @@ -674,13 +811,15 @@ sub cmpthese{ push @rows, \@row; } + return \@rows if $style eq "none"; + # Equalize column widths in the chart as much as possible without # exceeding 80 characters. This does not use or affect cols 0 or 1. my @sorted_width_refs = sort { $$a <=> $$b } map { \$_ } @col_widths[2..$#col_widths]; my $max_width = ${$sorted_width_refs[-1]}; - my $total = 0; + my $total = @col_widths - 1 ; for ( @col_widths ) { $total += $_ } STRETCHER: @@ -705,7 +844,7 @@ sub cmpthese{ printf $format, @$_; } - return $results; + return \@rows ; }